     bool  #(contains? #{true false} %)
     edn   (constantly true)
     regex #(instance? java.util.regex.Pattern %)
-    code  (constantly true)))
+    code  (constantly true)
+    file  #(instance? java.io.File %)))
 
 (defn- parse-fn [optarg]
   (fn [arg]

(ns boot.cli
  (:require
   [boot.util :as util]
   [clojure.string :as string]
   [clojure.pprint :as pprint]
   [boot.from.clojure.tools.cli :as cli]))

    bool  identity
    edn   (fnil read-string "nil")
    regex (fnil re-pattern "")
    code  (fnil (comp eval read-string) "nil")
    file  io/file))

(defn- assert-atom [type]
  (case type
